Independent boids

boids.cljs

(ns universe.core
  (:require [om.core :as om :include-macros true]
            [om.dom :as dom :include-macros true]))

(def app-state (atom {:text "Hello Boids"
                      :birds (map vector
                                  (repeatedly 20 #(rand-int 1000))
                                  (repeatedly 20 #(rand-int 1000)))}))

(defn make-bird [[x y]]
  (dom/circle #js {:cx x :cy y :r 12 :fill (str "rgb(" x ",150," y ")")}))

(defn flock [birds]
  (->> birds
       (map #(update-in % [0] (fn [x] (mod (+ x (rand-int 3)) 1000))))
       (map #(update-in % [1] (fn [y] (mod (+ y (rand-int 5)) 1000))))))

(defn make-map [circles]
  (apply dom/svg #js {:viewBox "0 0 1000 1000"} circles))

(defn main []
  (om/root
    (fn [app owner]
      (reify
        om/IRender
        (render [_]
          (dom/div nil
                   (dom/h1 nil (:text app))
                   (make-map 
                     (->> app
                          :birds
                          (map make-bird)))))
        
        om/IWillMount
        (will-mount [_]
          (js/setInterval (fn [] (om/transact! app :birds flock) 1000)))))

    app-state
    {:target (. js/document (getElementById "app"))}))